For the others it's hard to say they reached their maximum deltas since we don't know engine modes, but for RB we have a lower limit at least which suggest that they haven't lost anything in this regard despite the changes to the car. Promising.
It could even grow during race week when we know everything is turned up. I bet we'll see +28-29km/h during race week which is insane. Even at +28km/h, it is a significant improvement from the Rb19 due to the drag power scaling.
A lion must kill its prey.